That rallying cry — “I am Stephen Lynch” — is repeated by workers of different races and genders in the South Boston congressman’s newest television ad, meant to solidify the idea that the former ironworker who grew up in public housing is a candidate voters can relate to.

Implied in that message is the idea that working men and women cannot relate so easily to Edward J. Markey, Lynch’s rival for the Democratic Senate nomination, who has been a congressman for the last 36 years.

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The appearance of African-Americans declaring, “I am Stephen Lynch,” is also notable for a candidate from South Boston, a neighborhood steeped in Irish ethnic politics and riven by racial strife during the busing crisis of the 1970s.

“It seems to be an explicit move to say, ‘I want to be clear about my meaning here, in that when I talk about South Boston and my roots, I’m not talking about that particular history,’ ” said Charlton McIlwain, a New York University associate professor of media and culture who studies race and political messaging. “I’m talking about the way I see things now, which is a kind of solidarity that reaches across race and ethnic lines.’ ”

Jonathan Wiggs/Globe Staff

Representative Stephen Lynch

The ad — which begins airing Monday — is Lynch’s second to focus exclusively on his working-class roots.

Unlike his first ad, which featured several actors, this one uses real ironworkers and students, describing how their lives are like Lynch’s.

“I grew up in the projects, just like Stevie,” a man says, leaning against a brick wall in the Old Colony housing development in South Boston.

“I’ve been an ironworker for 15 years,” a man in a hard hat says. “Stephen Lynch was for 18.”

Markey, who is leading Lynch in early polls and is the favorite of the Democratic establishment, has focused his campaign more on issues than biographical narrative. His first ad highlights his opposition to assault weapons.

Lynch’s decision to focus solely on his biography is not unusual, however, particularly for a candidate who is not as well known as Markey among the broader electorate.

“You’ve got to make sure voters see the candidate as someone who has the stature and presence and ability to represent them at that level in the Senate, so that typically comes from biography, building that person up in personal terms,” said Tad Devine, a veteran Democratic strategist.

But the strategy carries some risk if the ads do not eventually broaden to include Lynch’s stance on issues, said Devine.

“If the story stops at biography, it’s probably not going to cut through with voters,” said Devine, who, like McIlwain, had not seen Lynch’s ad, but was told about its contents by the Globe. “The key is to take biography and attach it to a substantive agenda.

Lynch’s ads could also leave voters with the impression he worked his way through college and law school.

In the new spot, a young man with textbooks under his arm says Lynch went to college at night, “just like me,” and a young woman says Lynch then went to law school, “like me.”

Lynch graduated with a bachelor’s degree in construction management from Wentworth Institute in 1987, after attending classes at night.

But when he entered Boston College Law School, he was out of work and receiving payments from a disability settlement. Lynch had fallen 14 feet down a partially constructed stairwell, injuring a disc in his back.

“We’re not trying to hide that,” said Scott Ferson, a Lynch spokesman. “It was widely reported in 2001,” when Lynch first ran for Congress.

The goal of the ad, clearly, is to make the signature line “I am Stephen Lynch” linger. After several workers in the ad declare the line, the congressman appears, standing at a construction site.

“I am Stephen Lynch,” he says. “And I approve this message because I know how hard you work. And in the Senate, I’ll never forget it.”

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